Treatment of ovariectomized female rats with estrogen lowered plasma follicle stimulating hormone and luteinizing hormone 54 hr later and reduced the turnover of norepinephrine in the interstitial nucleus of the stria terminalis and central gray and of dopamine in the nucleus tractus diagonalis. Treatment of estrogen-primed females with progesterone at 48 hr elevated plasma gonadotropins at 54 hr and increased norepinephrine turnover in the intersititial nucleus of the stria terminalis, central gray and arcuate nucleus and increased dopamine tunover in the nucleus tractus diagonalis and interstitial nucleus of the stria terminalis. Estrogen plus progesterone decreased norepinephrine turnover in the ventromedial, periventricular and paraventricular nuclei.